Arrangement for tuning high frequency oscillation circuits



- July 22, 1941. w. BUSCHBECK 2,250,090

ARRANGEMENT FOR TUNING' HIGH FREQUENCY OSCILLATION CIRCUITS Filed Oct.5, 1959 2 Sheets-Sheet 2 ii l l I T -i, K cl W I i---- 4 'L J INVENTOR.WERNER B SCI/BECK BY ,d

' ATTORNEY.

Patented July 22, 1941 ARRANGEMENT FOR TUNING HIGH FRE- QUEN CYOSCILLATION CIRCUITS- Werner Buschbeck, Berlin, Germany, assignor toT'elefunken Gesellschaft fiir Drahtlose Telegraphic in. b. 11., Berlin,Germany, a corporation of Germany Application October 5, 1939, SerialNo. 297,978 In Germany September 28, 1938 7 Claims.

For the purpose of governing wider wave ranges without utilizingadditionally connectable rough adjustment means, the gliding variometerhas found its way more and more into the short ances of the grid circuitcertainly exist so that at acorrespondingly tuned anode circuit feedback eliects in accordance with the Huth-Kuehn principle, i. e.disturbance waves, in other words,

wave field. But such structures have the disadmay be produced owing tothe fact that a neuvantage that in the case of wider wave ranges ittralizing action no longer exists within this wave is, for instance, thewattless power of the interrange. Even though the resonance resistanceof mediate circuit which decreases with an increase the short couplingwave is low against that of in the wavelength owing to the pureinductive the long waves, a quantitative observation shows variation.Moreover, large inductances require 10 that in many cases the conditionfor the feed larger space and more structural means since the back willbe fulfilled. Hence, it should be aimed coil of the variometer is infact to be dimenat excluding in principle the self excitation at 'sionedfor the maximum current appearing at the short coupling wave. This isaccomplished the shortest wave and for the highest coil poaccording to afurther feature of the invention tential then prevailing so that thecoil will have by inserting a further inductance L5 (Fig. 4) excessivedimensions as regards the setting of the which is placed in series tothe parallel condenser higher inductance values. C4. In the case ofseveral parallel capacitances In accordance with the invention, thesedraweach of them is to be given obviously a respecbacks are avoided inthat parts of the variometer tive series inductance. The lower limitvalue of have one or several capacities connected in parthe shortcoupling wave now is practically deterallel thereto (Fig. 1) whereby thesaid capacities mined by L5 and C4 so that the short coupling are placedat those variometer turns which at wave will be moved definitely out ofthe region short waves are still short circuited. Therefore, of the gridresonance and it may eventually even in the case of short waves theparallel capacibe brought into the region of the actual operattances areinefiective. If the inductance is ining waves. The curves 0, d, e ofFig. 3 show the creased by shifting the variometer tapping, the powercurves for such cases in which the short parallel capacities havegradually impressed coupling wave is limited to about 9 In. Thesethereon potentials whose values increase in succurves indicate thatalready at the use of a single cession and thus they become ever moreeffecadditional capacitance the variation of the watttive. The case of asingle parallel capacity will less power of the intermediate circuit canbe next be considered. maintained very small as compared with the caseIf xmn designates a fictitious natural wave calof the simple variometerand that the required culated from capacities and inductances havingmaximum inductance can be reduced to a very the indices m and n, theresonance places of the great extent. It is clear that through the useof region according to Fig. 2 follow from the equaa further condenser arenewed raising etc. can tion: be brought about. More especially, it isalso The minus sign underneath the square root furpossible through asuitable variable dimensioning nishes the longer coupling wave, i, e.,the wave of the' stray capacity between the individual actuallycorresponding to the tuning. When turns of the coils to obtain anextremely flat and considering the limit condition, it is seen thatstepless pattern of the power curve. the short coupling wave starting atzero ap- In many cases, for instance, for push-pull proaches the limitvalue given by the series constages, symmetrical variometers L3, L3 andnection of C1 and C4 and L2. corresponding symmetrically connected addi-Fig. 3 shows for a practical example the watttional capacities willobviously be employed. As less powers of the intermediate circuit forcases shown in Fig. 5, it will be advisable in this case whoseadditional capacitances dilier in value as to compose the parallelcapacity of two parts indicated by the curves a and b.

The fact that the short coupling wave begins theoretically at zero, isin many cases an undesirable condition. At any short waves lying be- C4'and C4", each of which being symmetrical with respect to ground andwhose center is placed across a resistor at ground or at the directpotential. In this way a close coupling can be low the shortestoperating wave natural resonobtained between the upper and the lowerpart of the oscillatory circuit whereby asymmetrical conditions whichmay eventually be present, for instance, those of the coupling of theload will be compensated for. Furthermore, with this resistor a dampingor an eventual tendency to disturbance waves and the avoidance of staticcharges may be achieved.

It may eventually also be of advantage to represent the inductances andcapacitances shown in the circuit diagrams l to 5 by open lines andshort circuited lines such as shown by Way of exampl in Fig. 6. Such astructure offers an especially convenient possibility of supplying thecooling water at places at which the high frequency is grounded so thatadditional losses in high frequency due to the cooling water areavoided. Fig. 6 shows the variometer by the coaxial line L2 having thesliding tapping A. The inductance results from the magnetic fieldbetween the inner and outer conductors, and by means of the tapping Athis field is confined to the portion of the coaxial line L2 to the leftof the slider, i. e., between the slider and the anode end of theinductance. The line L2 is tapped at a suitable place by a transversalline W which consists of two different parts L5 and having differentwave resistances. The part L acts in this case as inductance and C4 actsas capacity. Such an arrangement has the particular advantage that straycapacities and stray inductances are entirely avoided such as isgenerally known when using coaxial lines as tuning elements ofoscillatory circuits. The cooling water may be supplied at K and passedoff at K.

The invention is not limited to its application for the tuning of shortwave transmitters but can be employed whenever at variations of theinduction capacitive variations are to be carried out at the same time.

What is claimed is:

1. An amplifier system including a vacuum tub having in its anodecircuit inductance and parallel capacity, and a fixed capacity fixedlyconnected in parallel to a portion only of said inductance, a relativelysmall inductance placed in series with said lastfixed capacity, andtapping means directly connected between the end of said firstinductance removed from said anode and. an intermediate point on saidfirst inductance for shortening out of said circuit an adjustableportion of said first inductance, said adjustable portion'including apart of that portion acrosswhich said fixed capacity is fixedlyconnected. I r

2. An amplifier system including a vacuum tube having inductance andparallel capacity in its output, and atleast one other capacitypermanently connected in parallel to a portion only of said inductance,and tapping means on said inductance extending between one end of saidinductance and the tapping point thereon for directly short circuitingan adjustable portion of said inductance, said adjustable portionincluding a part of that portion across Which said other capacity ispermanently connected.

3. An amplifier system including a vacuum tube having in its anodecircuit inductance and parallel capacity and a fixed capacity fixedlyconnected between the end of said inductance removed from said anode andan intermediate point, and tapping means on said inductance for directlyshorting out of said circuit an adjust able portion of said inductancebetween said end removed from said anode and the tapping point.

4. A transmitter including a vacuum tube having in its anode circuitinductance and parallel capacity, and a plurality of other capacitiesfixedly connected directly between the end of said inductance removedfrom said anode and different intermediate points on said inductance,and means for shorting out a portion of said inductance extending fromsaid one end of said inductance to any point on said inductance, wherebyas more and more inductance is effectively connected in said circuitmore and more capacity in shunt to portions of said inductance is alsoeffectively connected in said circuit.

5. An amplifier system including a vacuum tube having inductance andparallel capacity in its output, and a fixed capacity fixedly connecteddirectly across a portion only of said inductance,

and a single control in the form of a shortcircuiting member extendingbetween one end of said inductance and an intermediate point thereon forvarying simultaneously both the inductance and the effect of said lastcapacity in parallel to a portion of said inductance.

6. A push-pull amplifier system comprising a pair of electrodestructures each including a grid, an anode, and a cathode, an inductanceand a parallel capacity connected between the anode and cathode of eachof said structures, a capacity individual to each inductance and fixedlyconnected across a portion of each inductance, and tapping meansconnected between the cathode terminals of each of said inductances anda point on each of said inductances for directly short circuiting adesired portion of said inductances.

'7. An amplifier having an anode and a cathode, an output circuittherefor comprising fixed capacity connected between said anode and saidcathode and in parallel relation with said fixed capacity, a pathcomposed of an inductance having one end connected to the anode side ofthe capacity and an adjustable tap thereon connected to the other sideof the capacity, and another path including fixed capacity connectedbetween said cathode and a fixed point on said inductance intermediatethe ends thereof.

WERNER, BUSCHBECK.

